A frittata is an egg-based dish which includes other great additions like meat and vegetables. This frittata features delicious ham, spinach, onion, and spices to make it a one dish, yet memorable meal!
Whisk eggs and milk together in a large bowl until frothy. Add ham, spinach, onion, cheese, salt, dry mustard, and cayenne pepper. Whisk until well-combined.
Melt butter in a 12-inch cast iron skillet or baking dish. Pour frittata mixture into skillet and place into preheated oven for 10-12 minutes, until the frittata lightly browned and is set when the skillet is lightly jiggled. Remove from the oven and allow to sit for another 2-3 minutes to set completely before slicing and serving.